Electromagnetic relay



N 1946- s. H. TOWNER EI'AL ELECTROMAGNETIC RELAY Filed Nov. 6, 1945Patented Nov. 26, 1946 UNITE STATE AENT *GFMQE ELETRQMAGNETKC RELAYStanley Herbert Towner and Percy Arthur Childs,

London, England, assignors, by mesne assignments, to InternationalStandard Electric ilor- N. X., a corporation of radiation, New York,

Delaware Application November 6, 1943, Serial No. 509,216 In GreatBritain December 23, 1942 8 Claims.

13 The present invention relates to electromagnetic relays and isparticularly concerned with the improvement of the magnetic circuitofvibrating relays.

The relays with which the invention is concerned are of the kind inwhich the armature is carried by an elastic reed adapted to execute freevibrations at some definite frequency, or to be driven by alternatingcurrent which is applied to an operating winding and which may have thesame frequency as that natural to the reed. The reed hay controlcontacts which are periodically operated thereby.

The invention is directed to the improvement of the magnetic circuit ofthe relay whereby the operating winding is enabled to exercise a bettercontrol over the reed.

According to the invention, there is provided a magnetic circuit for anelectromagnetic relay having an armature carried by a vibratable reed,comprising a core adapted to carry an operating winding or win-clings, ayoke magnetically con nected to the core, and two pole-pieces, one beingbifurcated, with two substantially parallel limbs, the other pole-pieceand the armature being ar-= ranged between the said parallel limbs, thecore, yolse and pole-pieces being composed of magnetic material.

Two el bodiments oi the invention will be described i reference to Figs.1 and 2 of the ac\ company 1g drawing.

Fig. 1 shows a preferred embodiment. lhe

magnetic circuit of the relay comprises a core l on which any suitableoperating winding (not shown) be mounted having a pole-piece shaped inthe form of a U with two down-turned limbs 3A and 3B between which isplaced the other pole-*plece 5, which is constituted by the end of aportion of reduced width of the yoke which makes contact with the backend or" the core 3.

The vibrating reed is assembled below the yolre 5 by means not shown andcarries the armature l which is also placed between the limbs 3A and 3Bof one polepicce 2 and is normally spaced away from the pole-pieoe l.All the details l, 2, and i should be made of soft iron or othersuitable magnetic material.

The air spacing between the pole-piece 1 and the limbs and of thepole-piece should preferably be large compared with the spacing betweenthe armature l and these limbs, as indicated in Fig. l, in order thatthe magnetic flux may not be unduly shunted away from the armature. Thisarmature will then lie mainly in the normal path of the magneticpole-pieces and the reluctance odecreased as the armature approachespiece A l. If a suitable winding core l and is energised with estcurrent, the armature will be attracted towards the polethe polemountedon the piece E: and will ultimately rest thereon. When the energisingcurrent is cut oil, the reed will 1 preferably be arranged so that itwill hold the armature and reed in the fully deflected position when thewinding is continuously energised. This pole-piece assists in theinitial attraction of the armature, but has the maximum effect when theair gap is small.

The arrangement of Fig. 1 permits ture to be moved along the oi the reedwlthout appreciably affecting the efiiciency of the magnetic circuit.This feature is valuable, since it allows the vibrating system to betuned with out impairing the operation of he relay.

Fig. 2 shows a fragmentary sketch of a slightly different arrangement ofthe armature and polepieces according to the invention, which is exactlythe same in principle. The'back ends of the core and yoke 5 may be asshown in Fig. 1, and are not shown in Fig. 2.

The core l is provided with a plain pole-piece it which corresponds infunction with the polepiece ii of Fig. 1. A bifurcated pole-piece isprovided for the yoke 5 by means or" the blocks lSA and H33 of magneticmaterial fixed thereto and embracing the" pole-piece l the armature 7carried by the rec arranged below. It will be evident that the principaldifierericebetween Figs. 2 l is that the bifurcated pole-piece iscarried by the yoke instead of by the core. As in the case of Fig. l,the air-=gaps between the pole=piece ill and the blocks all and. 1328should preferably be large cor Jared with the armature air-gaps.

In either case, the limbs 3A, or will always have the same magneticpolarity, so that they constitute a single divided pole piece and notseparate pole-pieces It will be evident that the blocks lbs and I33could, if' desired, be formed integrally with the yoke 5. and in Fig. l,the limbs 3A and 33 could be separate pieces.

What is claimed is:

1. In an electromagnetic device in which a variable flux isproduced,means forming a magnetic circuit comprising, a substantiallyrigid core assembly having a double gap at which the flux divides intotwo substantially parallel paths, said double gap being formed by afixed central pole piece positioned between two rigidly connected spacedpole pieces with the gaps being formed on the opposite'sides of thecentral pole piece, and a vibrating armature formed by an iron piecepositioned with one face substantially parallel to one face of saidcentral pole piece and with two opposite edge faces parallel to andspaced from the respective faces of said spaced pole pieces, said ironpiece being mounted to vibrate in the planes of said edge facestransversely of the adjacent face of said central pole piece andparallel to the adjacent faces of said spaced pole pieces.

2. In an electromagnetic device, means forming a magnetic circuit havingan air gap therein comprising, a rigid core assembly having a double gapat which the flux divides into two parallel paths, said double gap beingformed by a central core portion positioned between a pair of parallelside core portion with each of the side core portions having a pole faceparallel to and adjacent a pole face of the central core portion wherebythe two parallel paths are'respectively from the abovementioned polefaces of the central core portion to the respective pole faces of theside core portions, and a vibratable armature positioned adjacent saidcentral core portion and adapted to vibrate toward and away from saidcentral core portion, said vibratable armature having edge portionswhich are positioned adjacent said side core portions during the timethat the armature is nearest said central core portion whereby a part ofthe magnetic flux in each of said parallel paths is diverted throughsaid edge portions of said armature.

3. In an electromagnetic relay,,the combination of, a core constructionadapted to carry an operating winding, a yoke magnetically coupled tothe opposite ends of said core construction and forming a magnetic pathfor the 1 iagnetic -flux of said core construction, said yoke having twopolepiece structures one of which is bifurcated with two parallel limbshaving opposing faces and the other of which is positioned adjacent saidlimbs, and a vibratable armature formed by a movable pole piece carriedby a vibrator reed with the movable pole piece positioned at'the edge ofthe zone between said limbs and mounted to vibrate parallel to theopposing faces of said limbs to and from said other pole-piecestructure.

4. A device as described in claim 3 wherein, said birfucated pole-piecestructure is formed by a single member attached to one end of said coreconstruction, and wherein said other pole-piece structure is an integralportion of an L-shaped yoke portion attached to the other end of saidcore construction.

5. A device as described in claim 3 wherein, said movable pole piece isadjustably attached to said vibrator reed whereby the natural frequencyof vibration of said vibratable armature may be adjusted.

6. A device as described in claim 3 wherein, Y

said vibratable armature has an elongated vibratable reed attached atone end to said yoke and carries said movable pole pieceadjacent itsother end, and wherein the natural frequency of vibration of saidvibratable armature may be changed.

7. A device as described in claim 3 wherein, said bifurcated pole-piecestructure is formed by a pair of separate pole pieces attached to a yokeframe member and wherein said other pole-piece structure is formed by asingle member attached to one end of said core construction.

8. A devic as described in claim 3, wherein said vibrator reed iselongated and is attached 40 to said core at one end and carries saidmovable core construction and yoke are formed of iron.

STANLEY HERBERT TOWNER. PERCY ARTHUR CHILDS.

